1. Field of the Invention
The present invention relates to a protection system for a turbo machine which detects abnormality of a turbo machine such as a steam turbine in a power generating facility and stops the turbo machine, and to a power generating equipment.
2. Description of the Related Art
In a power generating equipment or the like using a turbo machine such as a steam turbine, various protection systems are provided for the purpose of detecting, besides an abnormal phenomenon and failure, phenomena such as an elongation difference of a steam turbine, large vibration, high temperature in a low pressure exhaust room, low oil pressure of a bearing, low discharge pressure of a main oil pump, boiler/generator failure, and so on to prevent an accident from occurring or to minimize the damage due to the accident. Among these, an abnormal increase in a turbine rotation speed is the most important item, so that a protection system which detects the abnormal increase in a turbine rotation speed and stops the turbine is provided.
In a conventional protection system for a turbo machine, a transmitting means using oil pressure signals is generally used as a signal transmitting means. FIG. 11 shows a configuration of such a protection system for a turbo machine, and in the drawing, the numeral 1 denotes an emergency governor, and the numeral 2 denotes an emergency trip device placed in combination with the emergency governor 1. The emergency governor 1 includes an eccentric ring (or a pop-up pin) integrally incorporated in a rotation shaft of a steam turbine. Further, the emergency trip device 2 includes a latch mechanism 5 constituted of a trip finger 3 and a trip rod 4.
When the rotation speed of the steam turbine rises to a set rotation speed or above, a centrifugal force also occurs on the eccentric ring (or the pop-up pin) of the emergency governor 1 integrally incorporated in the rotation shaft of the steam turbine, and the eccentric ring turns to a mechanical deviation and moves. When the mechanical deviation (mechanical signal) of the eccentric ring becomes equal to a certain value or larger, the eccentric ring comes in contact with the trip finger 3 of the emergency trip device 2 and removes the latch mechanism 5 constituted of the trip finger 3 and the trip rod 4. As a result, the trip rod 4 is pushed out toward the emergency governor 1 side, which is detected as a mechanical deviation (mechanical signal) of the trip rod 4. This movement of the trip rod 4 of the mechanical type trip device is detected by a mechanical trip valve 10 and converted into an oil pressure signal.
This oil pressure is transmitted to a hydraulic drive mechanism or the like which drives a not-shown main steam stop valve via a hydraulic system constituted of a lock out valve 11, a master trip valve 12 and so on to thereby close the main steam stop valve (for example, refer to Japanese Utility-Model Laid-open Application No. Sho 61-114009).
In the conventional protection system for the turbo machine as described above, the transmitting means using oil pressures is used as the signal transmitting means, and it is a highly reliable system. However, there have been problems such that the use of oil pressures complicates the equipment structure, the use of high oil pressures can cause oil leakage, and improvement in performance such as transmission speed is limited.